SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/318924
Certain regions also experience the opposite of a salinity issue, in that some water sources do not have enough salts. Many inland regions of the U.S. have ground and surface water that is so low in salts that remedial actions are needed to alleviate the "salt-less" condition. Hurricanes and extreme storm events also introduce salts into soil and aquifers. Storm surge related flooding could directly induce salinity problems in land previously free of such issues via storm water runoff. Saltwater intrusion into subsoil and groundwater aquifers can increase when storms produce differential hydrologic heads. Salt removal can occur naturally, aided by rainfall and leaching, but extended dry periods fol- lowing such storm events often intensify negative salt effects on plants. Seasonal weather patterns (dry summers) may also induce temporary salt issues. During this period, salts may accumulate in the soil profile if not properly irrigated to leach the salts. Fortunately, this is an issue only in extreme cases, due to the returning rains in fall. Anthropogenic sources of sAlts in irrigAtion wAter Groundwater drawdown by urban and agricultural water use has contributed to saltwater intrusion into the underly- ing aquifer. Fresh water bodies that are influenced by tides are susceptible to saltwater intrusion occurring further upstream than normal as freshwater uses increase in urban areas. When this water is used for irrigation, it contributes to the salt levels in landscaped areas. In the future, reclaimed water (treated effluent) from municipal wastewater treatment plants may become the prevalent irrigation source for turfgrasses and landscapes. Many golf courses already use treated effluent as a primary irrigation source. Large planned communities also use treated effluent to irrigate municipal parks and sports fields, commercial areas, and residential lawns. Examples include Tradition Hilton Head in South Carolina, which uses storm water as well as treated effluent for irrigating turfgrass areas. Treated effluent from the Michelson Water Reclamation Plant in Irvine, California is used to irrigate school playfields, athletic fields, parks and other turfgrass areas. Many ball fields, school yards, and parks in St. Petersburg, FL are irrigated with reclaimed water. Many other examples exist, yet treated effluent is not the most common water source for sports fields. This is primarily due to the lack of infrastructure to pipe treated wastewater to the end user. However, as freshwater demands increase, it is likely that treated effluent will become the MVP in the irrigation game. One of the main issues with using treated effluent for irrigation is that disinfection residuals, typically chlorinators (e.g. chlorine gas and bleach (sodium hypochlorite)) may remain in treated solution. Low concentrations of chlorine and sodium can be problematic when used to irrigate plants. Emerging water treatment techniques use less of these disinfectants; however, the newer technologies require retrofitting or installation of new infrastructure, and thus are costly and will be implemented slowly. Although treated efflu- ent may have a higher salt content, they typically also have a higher nutrient content, which can (and should) be considered into a facility's fertility program (Table 2). For example, treated effluent from the Myrtle Beach Waste Water Plant (Table 2) will most likely supply adequate levels of phosphorus, potassium, and calcium for maintaining highly managed turfgrass. Although limited to those areas of the country that receive snow, it is noteworthy to comment on the salts contained in storm water runoff from roads deiced during winter storm events. The most commonly used deicers applied to roads are salt. Salts lower the melting point of water, causing the snow to melt in tempera- tures under which it would not typically melt. If the storm water runoff from our highway systems drains into a pond used for irrigation, the salts may concentrate over the winter making the water quite salty. What does this all mean? Knowing your water source(s) is the first step to managing salts. In the next installment of this series, we will investigate what makes salts (or the lack of ) such a problem for growing plants. ■ Dara M. Park, Ph.D. is an assistant professor, turfgrass, soil & water quality at Clemson University. Dr. White is the nursery extension specialist at Clemson. www.stma.org June 2014 | SportsTurf 35 parameter (units) # of Range Average samples analyzed ESSENTIAL NUTRIENTS Nitrate-N (ppm) 14 6.8 - 18 13.0 Ortho-P (ppm) 14 1.2 - 3.7 2.5 Potassium (ppm) 12 10.3 - 25.0 12.7 Calcium (ppm) 14 42.3 – 70.7 54.6 Magnesium (ppm) 12 3.5 – 4.0 3.8 Sulfate (ppm) 12 26 - 40 30.5 Sodium (ppm) 14 56 – 79 63.4 Chloride (ppm) 14 55.5 – 80.9 66.6 INDICATORS AND OTHER CONSTITUENTS pH 12 6.9 – 7.7 7.2 TDS (ppm) 12 384 - 467 418.8 EC (mmhos cm-1) 14 0.58 -0.73 0.65 SAR 12 1.9 – 3.1 2.3 Bicarbonates (meq L-1) 14 0.01 – 1.80 1.05 Carbonates (meq L-1) 14 0 – 0.33 0.05 RSC (calculated) 12 0.00007 - .008 0.005 Table 2. Mineral values in reclaimed water (treated effluent) used for irrigation from the Myrtle Beach Wastewater Treatment Plant.